Actually there is one bloody good source of gen available to all and sundry, the RAF Publications Library on t'intranet. It contains up to date copies of most of the scribbly APs. Granted as an EngO I probaly have more occasion to dig them up than most aircrew mates, as with a large flt I often have people with issues that make me want to see what the book says, but it's well worth knowing about for everyone. If you don't know where it is, on your Stn intranet home page, click "Royal Air Force" in the top right-hand corner, select "Publications" from the drop down menu and then "RAF" from the second menu. In this case you're after AP3392 Vol 2 Lflt 2002.
Rank for Retired Pay Purposes
13. The rank used for the calculation of Retired Pay will normally be the substantive rank held by the officer on his date of retirement provided that, unless he is invalided, the rank has been held on the Active List for the following minimum periods:
a. Air Chief Marshal - 1 year.
b. Air Marshal and below - 2 years.
If the substantive rank has been held for less that the specified period (for retired pay purposes Flt Lt (Specialist Aircrew) is considered a separate substantive rank), his Retired Pay will be based on the highest substantive rank which satisfies the condition, any periods served in a higher substantive rank being included in the calculation of the specified period.
Additions to Retired Pay
14. An officer whose rank for Retired Pay purposes is lower that his substantive rank on retirement will be awarded an addition to his Retired Pay for service in the higher substantive rank in accordance with QR 2933(1). The addition will be based on the difference between the Retired Pay for the rank awarded under para 13 above and the next higher rank on the basis that one year's service will qualify for one half of the difference between the 2 rates. Parts of a year in excess of one year will be counted proportionately.
15. If an officer has held paid acting or a temporary rank higher than his rank for Retired Pay purposes as defined in para 14 above, and such rank has been held for at least one year, he may be awarded an addition to the Retired Pay to which he is otherwise eligible, calculated as follows:
For each period (subject to a minimum of one year and a maximum of 3 years) for which the paid acting or temporary rank was held, an addition of one third of the difference between the Retired Pay for which the officer is otherwise eligible and the Retired Pay for which he would have been eligible had his rank for Retired Pay purposes been one rank higher. Such addition will be assessed on completed years and days.
The Defence Council may fix a date after which periods in paid acting and temporary rank may no longer count for additions to Retired Pay.